1. Field of the Invention
The present invention relates to a method and composition for absorbing wound exudate and filling a wound.
2. Description of the Related Art
In order to protect a wound during the healing process, typically, a sterile dressing is used. The dressing is often treated with a tissue adhesive for speeding the healing process. An ideal tissue adhesive is biodegradable, nontoxic, and readily absorbed so that it does not hinder the healing process. Hydrolyzed collagen has been found to meet all these requirements.
As the principal structural protein, collagen is the main component of connective tissue. Type I collagen makes up more than 90% of these tissues, including periodontal ligaments and gingiva tissue. Amino acid composition and sequence determine the properties of collagen that make it suitable for wound healing, especially in acute or chronic wounds, and in dental applications. Favorable characteristics of collagen include high tensile strength, orientation of fibers, semipermeability of membranes, low antigenicity, positive effect on wound healing, and hemostatic properties.
Hydrolyzed collagen is defined as a collagen hydrolysate polypeptide having a molecular weight of 1,000 to 10,000 derived by hydrolysis. Hydrolyzed collagen is commercially available in powdered form, or as an aqueous solution. Commercial preparation is accomplished by one of three methods: alkaline hydrolysis, enzymatic hydrolysis, or acid hydrolysis. Any of these methods may be used to derive collagen from either a bovine or porcine source As suggested above, amino acid composition and sequence determine the beneficial healing qualities of collagen. Hydroxylysine and hydroxyproline are two amino acids found only in collagen and not other medical protein hydrolysates. Hydroxylysine is typically found in concentrations from 0.7 to 1.2% in hydrolyzed collagen, while hydroxyproline is found at concentrations of 12.1 to 14.5% Because hydrolyzed collagen is well suited for use as a tissue adhesive, and accelerates the healing process, there is a need for a wound dressing using hydrolyzed collagen.
The use of medical hydrolysates and collagen in wound healing has been the subject of previous patents. U.S. Pat. Nos. 4,216,204 and 4,455,302, which issued to Robertson on Aug. 5 1980 and Jun. 19, 1984 respectively, disclose a medical protein hydrolysate and processes for making and using the protein hydrolysate. The protein hydrolysate is made in powder or gel form from young poultry feet for application to traumatized areas.
Other patents disclose the use of collagen in various wound dressings. U.S. Pat. No. 4,759,354, which issued to Quarfoot on Jul. 26, 1988, discloses a wound dressing including a vapor-permeable layer and an absorbent adhesive layer containing collagen. U.S. Pat. No. 4,837,024, which issued to Michaeli on Jun. 6, 1989, discloses compositions, articles and methods for improving wound healing. The wound is contacted by a combined suspension of collagen and a chemotactic glycosaminoglycan for improved healing. U.S. Pat. No. 4,950,699, which issued to Holman on Aug. 21, 1990, discloses a wound dressing incorporating collagen in an adhesive layer. U.S. Pat. No. 5,081,106, which issued to Bentley, et al. on Jan. 14, 1992, discloses a wound dressing protocol utilizing collagen gelatin formed with iodine. U.S. Pat. No. 5,116,620, which issued to Chvapil, et al. on May 26, 1992, discloses an antimicrobial wound dressing, having a layer of collagen impregnated with lyophilized, stabilized chlorine-containing compounds. U.S. Pat. No. 5,196,185, which issued to Silver, et al. on Mar. 23, 1993, discloses a collagen-based wound dressing and method of application. The dressing uses type I and/or type III collagen in an aerosol delivery system.
Other compositions and methods for aiding wound healing have also been the subjects of previous patents, but are less related to the present invention. Examples of previous patents describing wound healing are diverse: U.S. Pat. No. 4,813,942 (three step wound treatment method and dressing therefor) which issued to Alvarez on Mar. 21, 1989; U.S. Pat. No. 4,921,691 (spray on wound dressing compositions) which issued to Stockel on May 1 1990; U.S. Pat. No. 5,300,306 (tissue-equivalent membrane from bovine esophageal tissue) which issued to Alvarado, et al. on Apr. 5, 1994; European patent document 0 530 982 A1 (wound dressing for deep wounds) published Mar. 10, 1993; and European patent document 0 450 671 A1 (wound dressing and method of preparing the same) dated Oct. 9, 1991.
Although many wound dressings exist, there is still a need for a wound dressing and method of application using the beneficial properties of hydrolyzed collagen. None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed.